Neuroendogastrointestinal peptides act at various sites to modulate central nervous system (CNS), endocrine and gastrointestinal functions. The presence in or access to each of these tissues by such peptides is suggestive of their playing physiologic roles as members of a diffuse extracelluar messenger system. We have three major goals: 1. The isolation, chemical characterization and synthesis of new regulatory peptides including growth hormone releasing factor (GRF), corticotropin/beta-endorphin/beta-LPH releasing factor (CRF), mammalian bombesin-like peptide, big somatostatin and adrenal hyperglycemic factor. 2. The investigation of the physiologic and pathophysiologic roles of selected neuroendogastrointestinal peptides particularly as they modulate the functions of the anterior pituitary gland, pancreas and brain control of behavior, the sympathetic nervous system, and glucose metabolism. 3. The development of peptide analogs of these key regulatory peptides which can provide important investigational and clinical tools. Potent, long acting, orally effective, selective agonists and antagonists might be applied to the study, diagnosis or even therapeutic management of conditions such as diabetes mellitus, abnormal growth and development, cardiovascular disease, endocrine neoplasia, and behavioral disorders.